A 1200-kg car, initially moving at 20 m/s, comes to a stop at a red light over a time of 3 s from the moment the driver hit the brakes. What is the impulse delivered to the car by the static friction force (assumed constant) between the road and the tires

Mass of car (M) = 1200kg

Initial velocity (u) = 20m/s

Stop after time (t) = 3sec.

Come to stop implies that the final velocity is zero, v=0m/s

Using newton second law of motion

F=m (v-u) / t

Ft=m (v-u)

Since impulse is Ft

I=Ft

Then, I=Ft=m (v-u)

I=m (v-u)

I=1200 (0-20)

I=1200*-20

I=-24,000Ns

The impulse delivered to the car by static friction is - 24,000Ns